Quantum computational phases of matter - Stephen Bartlett

A recent breakthrough in quantum computing has been the realization that quantum computation can proceed solely through single-spin measurements on an appropriate quantum state. One exciting prospect is that the ground or low-temperature thermal state of an interacting quantum many-body system can serve as such a resource state for quantum computation. The system would simply need to be cooled sufficiently and then subjected to local measurements. It would be unfortunate, however, if the usefulness of a ground or low-temperature thermal state for quantum computation was critically dependent on the details of the system's Hamiltonian. A much more powerful result would be the existence of a robust ordered phase which is characterized by the ability to perform measurement-based quantum computation. I'll discuss some recent results on the existence of such a quantum computational phase of matter, including a specific realistic model in a spin-1 chain. Joint work with Gavin Brennen, Akimasa Miyake, and Joseph Renes.